by Jeff Zillgitt, USA TODAY Sports

"Greg epitomized what it meant to be an NBA Referee through dedication to his craft, hard work, and integrity both on-and-off the court," National Basketball Referees Association general counsel Lee Seham said. "He was not only a great NBA Referee, but more importantly a wonderful person, and our thoughts and prayers are with his family during this difficult time."

Considered one of the top NBA referees the past several seasons, Willard officiated more than 1,500 NBA regular-season and playoff games during his 24 seasons in the NBA. He earned respect from coaches and players, including Miami Heat forward LeBron James, for his ability and fairness.

"RIP to one of our NBA refs Greg Willard due to cancer! Prayers goes out to his family and friends #NBAFamily," James tweeted.

Last season, Willard reffed 51 regular-season and seven playoff games, including Game 1 of Western Conference Finals between the Oklahoma City Thunder and San Antonio Spurs on May 27 and Game 4 of the Eastern Conference finals between the Boston Celtics and Miami Heat on June 3.

On June 11, the National Basketball Referees Association released a statement saying Willard had been diagnosed with pancreatic cancer. He was scheduled to work a Finals game last season but had to withdraw due to his illness.

"The entire NBA family joins me in mourning the loss of one of our own, Greg Willard," NBA Commissioner David Stern said. "Greg touched all those with whom he came in contact thanks to his extraordinary spirit, dedication and hard work. As a Finals referee, he reached the highest level of his profession while at the same time demonstrating a strong commitment to his family and his community. Our thoughts are with his wife Laurie, their children and the rest of the Willard family during this difficult time."

For all Finals games between the Thunder and Heat, referees wore a No. 57 patch in honor of Willard, who called two Finals games during his career.

At the Pancreatic Cancer Action Network's annual event aimed at raising money and awareness on Oct. 20, Willard received the organization's Spirit of Hope award. Former NBA player and coach Kurt Rambis introduced Willard at the event.

On his web site, Rambis shared quotes from NBA players and coaches, including Kobe Bryant, Pau Gasol, Phil Jackson, Doc Rivers, Gregg Popovich, Pat Riley and David Stern. It was a testimony to Willard's professionalism on the court and his humanity off the court.

Willard attended the annual NBA referees camp in New York in late September and officiated a preseason game between the Los Angeles Lakers and Utah Jazz on Oct. 16.

At the beginning of the season, NBA coaches and referees wore purple wristbands that read, "Fight Pancreatic Cancer."